Use of Internal Jugular Vein POCUS to Assess Intravascular Volume Status: A Study in Critically Ill Pediatric Post-Operative Cardiac Patients.

Background: Understanding the intravascular volume status in critically ill children is challenging. Central venous pressure (CVP) is commonly used but is invasive. Assessment of both the inferior vena cava (IVC) and the internal jugular vein (IJV) by point of care ultrasound (POCUS) have shown significant correlation with CVP in adults. Limited data exists in pediatric patients, especially with IJV measurements. This study aims to correlate IJV POCUS with CVP in mechanically ventilated post-operative children following congenital heart disease surgery. Methods: This prospective study was conducted in the pediatric cardiac critical care unit at a tertiary children's hospital. In addition to other variables, IJV/common carotid artery (CCA) ratio at inspiration and expiration was calculated using the largest diameters of both vessels. The IJV distensibility index (%) was calculated as the ratio of difference in maximal IJV diameter during inspiration and minimal IJV expiratory diameter to minimal IJV expiratory diameter × 100. CVP was obtained prior to POCUS measurements. The association between CVP and the IJV/CCA ratio, as well as IJV distensibility, were assessed using correlation coefficients and 95% confidence intervals. Results: Thirty-one patients were included, with a median age of 2 months (IQR [0, 6]) and median CVP value of 8.5 mm Hg (IQR 6-11). No significant correlations were found between CVP and IJV/CCA ratio (R= 0.030 p= 0.87) and IJV distensibility index (R= -0.19 p= 0.31). Conclusions: Although utilizing IJV POCUS to assess volume status may be advantageous given the limited access to IVC measurements in post-operative pediatric cardiac patients, our preliminary data suggests limited utility. Larger-scale studies are needed to establish a more definitive relationship between these variables.